Dear Plant-edders,
That rat might be the first tetraploid mammal, but I don't think it is
the first evidence of tetraploidy in animals. Fish are much like plants
in that fertilization is external. This provides a much greater
opportunity for hybridization. I have a vague recollection of this being
true in Salmonids, so I asked our fish biologist. Here is his offering on
the subject.
> I thought I remembered that also about the salmonids so I did a quick
> search to confirm it. From the sounds of the abstract that I copied below,
> it must contain references that document tetraploidy in the salmonids.
> Once again, it sounds like fish win another round in the interesting
> diversity game. That is until the plants and insects join the contest!
>> -Casey
>> TITLE: Sequence of sockeye salmon type 1 and 2 growth hormone genes
> and the relationship of rainbow trout with Atlantic and
> Pacific salmon.
> AUTHOR: Devlin, R. H.
> AUTHOR AFFIL: Dep. Fisheries and Oceans, 4160 Marie Dr., West
> Vancouver, BC
> V7V 1N6
> COUNTRY: CAN
> SOURCE TITLE: Canadian Journal of Fisheries and Aquatic Sciences
> SOURCE: 50, no. 8 (1993): 1738-1748
> DOCUMENT TYPE: Article
> STANDARD NO: 0706-652X
> YEAR: 1993
> LANGUAGE: English (EN)
> SUMMARY LA: English (EN); French (FR)
> ABSTRACT: Two types of growth hormone genes have been isolated from
> sockeye salmon (Oncorhynchus nerka) and their complete
> nucleotide sequence determined. The genes encode
> proteins of
> 210 amino acids and show considerable similarity to
> growth
> hormones characterized in other salmonids and fishes.
> The two
> genes presumably arose from a gene duplication event that
> generated the tetraploid condition in salmonids and are
> highly conserved in their coding regions. The sequences
> have
> diverged approximately 18% in noncoding regions since the
> gene duplication event and show numerous deletions and/or
> insertions. Isolation of these two genes from a Pacific
> salmon allows comparison of their sequences to growth
> hormone
> genes characterized from rainbow trout and from Atlantic
> salmon. The results indicate that rainbow trout is more
> similar to Pacific than to Atlantic salmon and suggest
> that
> Atlantic salmon diverged from Pacific salmonids at a time
> when sockeye and rainbow trout were part of a common
> breeding
> population. These results support the recent
> reclassification
> of rainbow trout from the genus Salmo to Oncorhynchus.
> MAJ CONCEPT: Biochemistry and Biophysics; Endocrine System; Genetics;
> Methodology; Reproductive System
> SUPER TAXA: Osteichthyes: Pisces, Vertebrata, Chordata, Animalia
> TAXA NOTES: animals; chordates; fish; nonhuman vertebrates;
> vertebrates
> ORGANISM: Oncorhynchus nerka (Osteichthyes); Osteichthyes
> (Osteichthyes); Salmo (Osteichthyes)
> SEQ DATA: molecular sequence data; nucleotide sequence
> MISC DESCRIPT: AMINO ACID; BREEDING POPULATION; PROTEIN; TETRAPLOIDY
>Janice
***********************************
Janice M. Glime, Professor
Department of Biological Sciences
Michigan Technological University
Houghton, MI 49931-1295
jmglime at mtu.edu
906-487-2546
FAX 906-487-3167
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